Asbestos standards: TRGS, VDI, IFA, CARB at a glance

Annex 2, Procedures 1 through 4. The annex describes four analytical procedures, suited to different material characteristics, for determining asbestos mass content under Annex II No. 1 GefStoffV:

• Procedure 1: direct analysis of the bulk material (suitable for homogeneously distributed asbestos in solid matrices).
• Procedure 2: determination of asbestos mass content referenced to the falling mass. This is the operative procedure for bulk granular materials (gravel, chippings, sand). A standardised dustability test simulates the worst-case pouring or unloading event; the respirable dust (E-Staub, the lung-penetrating fraction) is generated and weighed. The asbestos content of the respirable dust is determined per IFA 7487 (SEM/EDX). The formula [asbestos mass fraction in dust] × [mass fraction of respirable dust in the falling sample] yields the "asbestos mass content referenced to the falling mass, i.e. the asbestos mass content of the material as used".
• Procedures 3 and 4: specific procedures for particular material types and preparation states; full descriptions in the Annex 2 text.

Repetition requirement. For each material at least three determinations must be carried out at intervals of at least 30 days. No individual result may exceed 0.1 % by mass; otherwise the material is classified as asbestos-containing under the Hazardous Substances Ordinance.

Cross-references within the German regulatory framework.

• TRGS 519 governs ASI work (demolition, sanitation, maintenance) on asbestos-containing materials. TRGS 519 presupposes that asbestos has already been identified, typically via TRGS 517 or VDI 3866.
• TRGS 910 defines the acceptance and tolerance concentrations for asbestos fibres in workplace breathing air (acceptance concentration 10,000 F/m³).
• Annex II No. 1 GefStoffV is the legal basis for the 0.1 % by-mass threshold; TRGS 517 provides the technical concretisation of the obligations under that annex. For the full regulatory chain (GefStoffV → TRGS 517 → Austria → REACH) see Regulatory framework.

Analytical laboratory step. The respirable-dust analysis required by Procedure 2 follows IFA Procedure 7487 using SEM/EDX. IFA 7487 is therefore an analytical procedure referenced inside TRGS 517, not a stand-alone material standard.

Structural logic. TRGS 519 broadly distinguishes between work of limited extent (smaller dismantling or repair operations on individual components) and larger ASI work (sanitation of whole building sections, asbestos-cement roofs, sprayed-asbestos sanitation). Each category has its own training requirements, protective measures, supervisor qualifications, and notification obligations.

Proof of expertise (Sachkundenachweis). Personnel who plan or execute ASI work on asbestos-containing materials require a recognised certificate of expertise. Contents and hour counts are defined in the annex to TRGS 519 and differ by function (supervisor, executing worker, work of limited extent).

Notification. An employer who plans ASI work must notify the competent authority in writing in good time before commencement. The notification specifies the location, type, and extent of the activity, the procedures applied, and the protective measures.

Protective-measures hierarchy. In this order: substitution or avoidance of the task; containment of the work area (negative-pressure enclosure, clean/dirty airlocks); emission-reducing work practices (wetting, local extraction); personal protective equipment (respirator, protective suit). The order is not optional.

Disposal. Asbestos-containing waste must be classified as hazardous waste. Packaging, labelling, and transport follow the waste-law regulations (in Germany the Abfallverzeichnis-Verordnung; in Austria the Abfallverzeichnis-Verordnung 2003 together with the AWG 2002; transport by ADR with the relevant UN numbers and special provision SV 168).

Relationship to TRGS 517. TRGS 517 answers the question "does this material contain asbestos above the threshold?". TRGS 519 answers "if so, how is the subsequent work to be done?". The two are complementary, not overlapping.

Austrian context. Austria does not have its own TRGS series; TRGS 519 is nonetheless used in practice as a technical reference standard, complemented by the Grenzwerteverordnung (GKV) and the ÖNORM series. The current GKV version excludes private individuals from the circle of persons authorised to carry out asbestos sanitation.

Why this disambiguation matters. In German and Austrian technical discussions the TRGS series is often cited in block form ("TRGS 517/519/521"). Historically this is not wrong, because the older TRGS 521 (1996 version, "Activities involving fibrous-dust substances") did cover asbestos. With the 2008 re-issue the scope was narrowed to old mineral wool, because asbestos is fully covered by TRGS 519 and no longer fit into the TRGS 521 logic.

WHO fibre criteria. The critical fibre dimensions are broadly uniform (length ≥ 5 µm, diameter ≤ 3 µm, length-to-diameter ratio ≥ 3:1). The distinction between carcinogenic old mineral-wool fibres and biosoluble modern MMVF is not geometric but rests on biosolubility, that is, the fibre's biological half-life in physiological medium. This distinction is the central differentiator between TRGS-521 scope and unregulated modern insulation.

Relationship to TRGS 519. Both standards regulate ASI work on health-hazardous fibrous materials, but on different substance groups: TRGS 519 on asbestos-containing materials, TRGS 521 on old mineral wool. Their protective-measures hierarchies are structurally similar; specific training and notification requirements differ. Mixed situations (where asbestos and mineral wool are installed together) are handled in practice under whichever rule is stricter.

Austrian context. As with TRGS 519, there is no direct Austrian counterpart; relevant requirements derive from the Grenzwerteverordnung, the Worker Protection Act (ArbeitnehmerInnenschutzgesetz), and applicable ÖNORM guidelines for building sanitation.

Character of the series. VDI 3866 yields a qualitative result (asbestos yes/no, which mineral species) and a semi-quantitative mass-content classification in bands (typically "mass class 1" for below 1 %, "mass class 2" for 1 to 5 %, "mass class 4" for 20 to 50 %, etc.; exact band thresholds are defined in the original text).

Detection limits. VDI 3866 Sheet 5 (SEM/EDX) achieves a detection limit of approximately 1 % by mass with standard sample preparation; with extended preparation (higher evaluation effort) this drops to approximately 0.1 % by mass (Ries 2024). For comparison: IFA 7487, optimised for powders and dusts, reaches a detection limit of approximately 0.008 % by mass, roughly an order of magnitude below VDI 3866's extended-preparation limit.

Morphological fibre classification. In analytical practice, three fibre-morphology types are distinguished (Ries 2024):

• Type A: fibres with a high aspect ratio and obvious lengthwise cleavage. Typical of industrially processed chrysotile, amosite, and crocidolite (the classic industrial asbestos minerals).
• Type B: prismatic amphibole forms (actinolite, tremolite, anthophyllite). The acicular crystals satisfy the WHO fibre geometry but are geologically grown, not industrially processed. These forms dominate in the Burgenland context (serpentinite occurrences in the Rechnitz window).
• Type C: short prismatic fragments produced by mechanical processing (crushing, grinding, traffic abrasion). These particles may fall below the WHO fibre length of 5 µm and are then not captured in standard fibre counting, even though they are mineralogically asbestos.

The distinction matters because Type C fragments are precisely what mechanical wear of serpentine aggregate by traffic produces over years. Standard fibre counting per WHO criteria captures them only if they exceed the geometry thresholds.

TEM as an alternative procedure. Besides the SEM/EDX method established in Germany and Austria (VDI 3866 Sheet 5), transmission electron microscopy (TEM) is used internationally. TEM is notably the French standard approach and offers higher resolution for very fine fibres, but is more equipment-intensive and less widespread in the German laboratory landscape (Ries 2024).

Method selection by material. In practice the method is chosen by matrix characteristics: phase-contrast light microscopy (Sheet 4) is fast and cost-effective but unreliable for very fine fibres and narrow fibre diameters; scanning electron microscopy (Sheet 5) is the reference method for disputed cases and for materials with low fibre content, though more involved; IR spectroscopy (Sheet 2) is suitable for certain homogeneous matrices as a complementary method. Accredited laboratories select per sample.

Relationship to TRGS 517. TRGS 517 Annex 2 references IFA Procedure 7487 (SEM/EDX) for analysing the respirable dust in Procedure 2. VDI 3866 Sheet 5 covers the same procedural class in a broader application context (technical products generally, not only the respirable-dust fraction of a dustability test). In accredited laboratory practice the two procedures are methodologically very close.

Method selection by material (example logic). In DAkkS-accredited laboratory practice, the method is selected by the sample's matrix characteristics. A rough heuristic:

• Solid homogeneous samples (fibre cement, plaster, floor adhesive): start with phase-contrast light-microscopy preliminary examination (Sheet 4); on suspicion or contested result, escalate to SEM-EDX (Sheet 5).
• Bulk granular materials and aggregates (gravel, chippings, sand): direct entry with SEM-EDX (Sheet 5) is common, since particle and grain-size distribution are inadequately resolved by light microscopy.
• Very fine powders and dusts (e.g. dusts from air sampling, knocked-off building-component dust): SEM-EDX (Sheet 5) in parallel with the IFA 7487 evaluation procedure, which was developed precisely for this sample type.
• Material mixtures with organic matrix (adhesives, sealants): preceded by chemical preparation per Sheet 1 to remove the matrix, then SEM-EDX per Sheet 5.

This method-selection logic is detailed in the VDI original text; the heuristic above summarises the selection logic for orientation.

Full-text note. The VDI guidelines are available through the Beuth-Verlag or the VDI portal for a fee. Detailed procedural steps (sample preparation, grain-size fractionation, filter loading, evaluation protocol) are described in the VDI original text; a comprehensive public reproduction of these steps is not available.

Discursive context. The suitability of VDI 3866 for naturally occurring asbestos in rocks has been contested in technical discussions (see for example OTS press releases by the ARGE Naturgestein in April 2026, taking the position that VDI 3866 is "unsuitable for natural rock"). We document that discussion elsewhere (Burgenland page, open letter to Prof. Kirschbaum). On the substance:

• VDI 3866 Sheet 5 is, in the majority of DAkkS-accredited laboratories, the practical standard for asbestos determination in material samples, including naturally occurring asbestos.
• The ARGE position that TRGS 517 is the "correct" method refers to the scope of the processing activity in the quarry/plant. Whether gravel that has been mechanically stressed by traffic for years can still be regarded as material "in processing" within the meaning of TRGS 517 is methodologically open (see Methodological context).
• California's CARB Method 435, developed explicitly for serpentine aggregate in road surfaces, resolves this by fully pulverising the sample before evaluation (PLM rather than SEM; see CARB Method 435). The question posed by VDI 3866 ("which asbestos minerals does this material sample contain?") is independent of that and methodologically correct for identifying the fibre species present.

WHO fibre definition. VDI 3492 counts fibres per the internationally established WHO criteria: length ≥ 5 µm, diameter ≤ 3 µm, length-to-diameter ratio ≥ 3:1. Only fibres meeting this geometry enter the concentration calculation; shorter or thicker particles are counted but classified as not lung-penetrating in the strict sense.

Pump parameters and minimum volume. The required air volume depends on the expected concentration; indoor clearance measurements typically need several hundred litres, ambient outdoor measurements correspondingly larger volumes. Exact parameters (pump rate, filter material, evaluated filter area) are described in the VDI original text; a comprehensive public reproduction of these steps is not available.

Detection-limit dependence. The analytical detection limit of a single measurement scales inversely with the evaluated air volume and the evaluated filter area. Lower detection limits require larger sample volumes and/or larger evaluated areas, increasing measurement time and cost.

Relationship to other air-measurement procedures. At European level, ISO 14966 is the harmonised international counterpart for SEM-based fibre counts in ambient air. VDI 3492 is used as the national standard in Germany and Austria, often specified to be methodologically compatible with ISO 14966. For workplace breathing air, the complementary BGI/GUV-I procedures (BGIA/IFA Kennzahl 7487 for SEM/EDX) are also in use.

Equipment and sampling parameters (orders of magnitude). Orientation values can be derived from publicly available methodological literature: pump rates typically 1 to 4 l/min for indoor measurements and 5 to 20 l/min for ambient air, sampling duration several hours to 24 hours depending on target concentration, filter material gold-sputtered polycarbonate membrane (typical pore size 0.8 µm) for the subsequent SEM analysis. The exact values are defined in the VDI original text and in the national-application annexes.

Detection-limit scaling. The typical detection limit for VDI 3492 is of the order of 300 F/m³ at common sampling volumes (Ries 2024). The analytical detection limit of a single measurement scales linearly with both the evaluated air volume and the evaluated filter area. Concretely: low detection limits in the range of a few F/m³ require air volumes > 1,000 litres and evaluated filter areas of several mm². For clearance measurements after asbestos sanitation, values below 500 F/m³ are typically achievable; for resident-background ambient measurements, orders of magnitude of 50 to 200 F/m³ are reported as background.

Application contexts and scope boundaries. Classical fields: clearance measurements after asbestos sanitation (indoor, against 100 to 500 F/m³ specifications by standard), indoor measurements for asbestos suspicion (schools and healthcare facilities), resident ambient-air measurements around sanitation and quarry sites (as used by the state Task Force Burgenland and in Szombathely). Not in scope: organic fibres (e.g. glass fibres must be confirmed as inorganic via EDX elemental spectra), material analysis (see VDI 3866), workplace measurements per the industrial standard (see TRGS 910 and IFA 7487).

Burgenland context. Both the state Task Force's 66-point winter measurement series (March 2026) and the Hungarian authority measurements in the Oladi-plató residential area in Szombathely (with values between 34,800 and 292,000 F/m³ under dry conditions, as reported by the competent Hungarian authority) were conducted using SEM-based procedures in the VDI 3492 tradition or compatible ISO standards. Measurement protocols are not in all cases publicly available.

Structure of the series. VDI 3877 consists of two sheets: Sheet 1 describes sampling (stamp/contact sample via adhesive medium), SEM/EDXA analysis, and documentation of results. Sheet 2 covers sampling strategy (how many samples, where, in what grid), interpretation of results, and provides recommendations for action.

Relevance for the Burgenland case. VDI 3877 would be methodologically applicable for quantifying surface contamination in indoor spaces or on playground equipment near asbestos-containing gravel roads. To date, no publicly documented VDI 3877 measurements in the context of the Burgenland case are known.

Full-text note. The VDI 3877 guideline is available through the Beuth-Verlag or the VDI portal for a fee. The procedural steps described here are based on the publicly available summary on the VDI portal page and on secondary sources from accredited testing laboratories.

Sample preparation. The powder or dust sample to be analysed is suspended (typically in ultrapure water with a surfactant additive), filtered, dried, and prepared for SEM examination (sputter coating with gold or carbon for electrical conductivity). Evaluation areas are distributed statistically across the sample to ensure representativeness.

Evaluation criteria. Identification as an asbestos fibre follows the WHO geometric criteria (length ≥ 5 µm, diameter ≤ 3 µm, L/D ≥ 3:1) and EDX confirmation of mineral type. Chrysotile is dominated by Mg and Si in the spectrum; amphibole asbestos species (actinolite, tremolite, anthophyllite, amosite, crocidolite) show Fe, Mg, Ca, and Na in characteristic ratios depending on the mineral.

Detection limit. The detection limit is a function of the evaluated filter area, sample quantity, and chosen magnification. Typical detection limits lie in the low parts-per-thousand to hundredths-of-a-per-mille range; specific values are defined in the relevant sampling specification (e.g. TRGS 517 Annex 2 or laboratory work instructions).

Relationship to internationally comparable procedures. IFA 7487 is methodologically closely related to the SEM procedures in VDI 3866 Sheet 5 (material analysis) and VDI 3492 (air measurement), as well as to ISO 22262 (internationally harmonised procedures for asbestos in bulk samples). The procedures differ primarily in sampling and sample preparation, not in the microscopy-spectroscopy evaluation step itself.

Relationship to CARB Method 435. CARB Method 435 uses polarised-light microscopy (PLM) with point-counting, not SEM. Both procedures determine an asbestos mass fraction in a pulverised sample; IFA 7487 with higher mineralogical confirmation confidence via EDX, CARB 435 with statistically robust point-counting across 400 particles. The procedures are not directly equivalent; a systematic comparative measurement on identical samples would be methodologically interesting but is not fully documented in publicly available technical literature.

Sampling by application context. CTM-029 / Method 435 specifies three distinct sampling scenarios:

• Serpentine Aggregate Storage Piles: multiple sub-samples from different heights and sides of the pile, combined into a composite sample.
• Serpentine Aggregate Conveyor Belts: sampling from the running belt over defined time intervals, similarly combined into a representative composite.
• Serpentine Aggregate Covered Surfaces: sampling from trafficked or walked surfaces such as unpaved roads, shoulders, and parking lots.

Sample preparation. The composite sample is ground and sieved to 200 Tyler mesh (≤ 75 µm). This pulverisation is the methodological core of the procedure: instead of measuring a situational respirable-dust fraction, the entire material is analytically transferred into the state it would be in after complete mechanical comminution. The resulting powder aliquot is transferred into a sealed sample container and handed to the laboratory.

Polarised-light microscopy evaluation. From the powder sample, a microscopy preparation is made; the polarised-light microscope is set to the optical properties of asbestos minerals (birefringence, extinction, refractive index). 400 randomly distributed particles in the field of view are counted; the fraction of identified asbestos fibres in this sub-sample yields the asbestos mass fraction of the sample. Detection limit 0.25 %.

Regulatory framework. CARB Method 435 is the analytical counterpart to the Asbestos Airborne Toxic Control Measure for Surfacing Applications, codified in 17 CCR § 93106. The regulation requires that "Restricted Material" for surfacing applications have an asbestos mass content of less than 0.25 % (current version since 2001). The original 1990s version permitted up to 5 %; the strengthening was adopted by CARB in July 2000 on the reasoning that the risk from decades of resident exposure was not sufficiently addressed at the higher value.

Methodological logic in comparison to TRGS 517 Annex 2. TRGS 517 Annex 2 Procedure 2 assesses the asbestos fraction in the situationally generated respirable dust of a standardised processing event and rescales that fraction to the falling mass. CARB Method 435, by contrast, analytically pulverises the entire sample and determines the asbestos fraction of the resulting homogeneous powder. The two procedures therefore answer two different questions: How much asbestos is released in a single processing event? versus How much asbestos does the material contain in total, if fully comminuted?

Geological background. California has documented NOA occurrences in serpentine-bearing formations, notably along the western Sierra Nevada foothills, in El Dorado County, Calaveras County, and Marin County. This geological situation is structurally comparable to the Burgenland and western-Hungary finding (Rechnitz window): dark-green serpentine-containing material, historically distributed as gravel and chippings.